Refrigerant feed control



Patented Feb. 25, 1936 ITED STATES PATENT OFFICE REFRIGERANT FEEDCONTBQL Application April 30,

10 Claims.

This invention relates to a refrigerating system employing one or moreevaporators or cooling coils for producing the cooling effect, thenumber of evaporators in the system being dependent .upon the amount ofrefrigeration required.

Heretofore certain types of evaporators, especially those formed ofrelatively long lengths of tubing and carrying heavy refrigeratingloads,

have been found difiicult to flood and if operated flooded, largequantities of entrained liquids are carried over with the suction gaswhich entrained liquid has been found difficult to provide for.

It is an object of the present invention to provide a refrigeratingsystem having means for automatically controlling the supply ofrefrigerant from the condenser, for automatically controlling thecirculation of the refrigerant in the cooling coils to produce thedesired refrigerant effect, for automatically maintaining the fluid orother substance refrigerated at a definite temperature, and for securinga flooded condition in the coils.

A further object of the invention is to provide a system in which lineadjustment of expansion valves or the like is avoided and, where the adjustment permits liquid to pass over with the gas, the system isarranged to handle the entrained refrigerant.

Other objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing wherein,

Fig. l is a diagraatic view illustrating one application of theinvention.

Fig. 2, a similar view of a modified form.

Referring to Fig. l of the drawing, compressed refrigerant is dischargedfrom a compressor it through a pipe ii to a condenser I]? where it isliquefied. Liquid refrigerant passes through pipe 40 63 to evaporatorcoil it where evaporation occurs and heat is absorbed thereby.

The refrigerant vapor is sucked back to the compressor through suctionline it, accumulator ii and suction line it. The above describedelements are in themselves of usual or conventional construction andform no part of the present invention. Furthermore these elements may beof any desired construction other than that illustrated, for example,the coils id and it may be of double pipe construction for coolingliquids.

The flow of liquid refrigerant through pipe it is controlled by anautomatic valve ll, connected by pipes 22 and 23 respectively with theupper portion of the accumulator and a depending liquid receiving pipeit, operates responsive to 1935, Serial No. 19,084

liquid level. The liquid refrigerant passing the valve ll flows throughpipe I 3' and expansion valve is into the lowermost turn of the coolingcoil Hi.

The expansion valve I9 is preferably of the adjustable type in orderthat it may be set as desired to permit expansion from the high to thelow side of the system.

From the upper portion of the coil ill into which the refrigerant hasbeen admitted from the pipe l3 through expansion valve it the gaseousrefrigerant, after having performed its refrigerating function andabsorbed heat, is sucked back to the compressor through pipe i5,accumulator ll and suction line it. Along with this gaseous refrigeranta quantity of entrained liquid will be carried and the entrained liquidwill be separated by gravity from the gaseous refrigerant and depositedin the accumulator ll.

Liquid in the accumulator ill will drain downwardly into pipe 2E3 whichis connected at its lower end to the bottom portion of the lower orsecondary evaporating coil it. The upper portion of the coil l5 has aconnection 2!! with the suction line it so that refrigerant gas will besucked from the coil it at the same time that it is sucked from the coilM and entrained refrigerant may also be carried into the accumulatorthrough the pipe 2i from the coil i5.

Expansion valve i9 is preferably manually set to give the correctquantity or an amount slightly in excess of the correct quantity of theliquid refrigerant which will just entirely evaporate in both of thecoils i l and it. Any slight excess of refrigerant withdrawn 'from thecoils it and iii and. trapped out in the accumulator can be readilyreturned by gravity to the lower coil it because this coil is made of alength and size such that the pressure drop under the desired operatingconditions, is not too great to overcome vthe gravity head of liquidfrom the accumulator and thereby prevent its return.

Fine adjustment of the expansion valve ill is not required due to thefact that if the adjustment of the valve is excessively wide it permitsa greater flow than is necessary. The liquid level will rise in pipe itand after the pipe 28 is filled the system will gradually become filled.When the liquid level has risen above a predetermined point the valve llcloses and by so doing prevents excess refrigerant from flowing into theevaporator coils. Accordingly liquid will no longer be entrained withgas withdrawn from the evaporator coil iii to further fill up the pipe20 or accumulator iii and with the absorption of heat the chamber 42.

the supply of liquid refrigerant in the evaporator coil l5, pipe 29, andaccumulator l1, will be evaporized or boiled off and the vapor suckedback to the compressor until the quantity of liquid refrigerant isreduced sumciently to cause reopening of the automatic valve H.

In Fig. 2 is shown a refrigerating system similar to that of Fig. 1 butmodified to the extent of employing an additional evaporator coil andmodified accumulator construction. According to the construction of Fig.2 a compressor 25 discharges compressed refrigerant through pipe 26 intoa condenser 21 where the refrigerant is liquefied. The refrigerant fromthe condenser 21 passes through pipe 28 to an evaporator consisting ofcoils 29, 30 and 35 which coils like those of Fig.1 may also be ofconventional construction. Refrigerant vapor is withdrawn from the upperpart of coils 29 and 39 through a suction line 32.and from the coil 3|through a suction line 33, both lines 32 and 33 discharging into anaccumulator 34 from whence refrigerant vapor is sucked through pipe 35back to the compressor.

Flow of liquid refrigerant through the liquid line 28 is controlled byan automatic valve 36 connected by pipes 31 and 38 with the accumulatorand which operates responsive to liquid refrigerant level similar tovalve H of Fig. 1. When the automatic valve 36 is open refrigerant flowspast the expansion valve 39 into the bottom of the upper coil 29. Theexpansion valve 39 is preferably of the adjustable type similar to valvei9 of Fig. 1 and is capable of being manually set to permit expansionfrom the high to the low side of the system. I Y

The accumulator 34 is provided with a partition 40 which divides theaccumulator into chambers 4| and 42, the automatic valve 36 beingadapted to close when the liquid level in the chamber 4| reached apredetermined height. On the low side of the system adjacent the valve39 is located an electrically operated valve 43 controlled by athermostat 44 from a thermostat bulb 45.

Refrigerant gas and entrained liquids are withdrawn from the evaporator29 through pipe 32 to chamber 4| of the accumulator where liquid and gasare separated, the gaseous refrigerant being sucked through pipe 35 tothe compressor and the liquid refrigerant draining by gravity throughpipe 46 into the bottom of the second or intermediate evaporator coil 39from which refrigerant vapor and entrained liquid are drawn through pipe32 into the accumulator.

The baffle 40 in the accumulator terminates near the bottom of theaccumulator and refrigerant in the chamber 4| fiows past the baflie intoLiquid refrigerant from the chamber 42 flows downwardly through pipe 41"into the bottom of the evaporator coil 3| from which gaseous refrigerantand any. entrained liquid is carried through the pipe 33 into thechamber 42 of the accumulator. Vapor from the chamber 42 of theaccumulator is withdrawn through pipe 48 into the suction line 35extending to the compressor.

A thermostatically operated valve 49 controls.

the suction of the refrigerant gas through the pipe 43 from the chamber42 to the compressor 25, the valve 49 being controlled from any desiredpoint in the circuit by a thermostat 59 having a bulb 5| in thermalcontact with fluid or other substance being cooled and the thermostatbeing set to operate the valve-when the temperature drops below apredetermined value. It is to be 29, 30 and 3| without damage.

understood that other types of valves which can be operated inaccordance with temperature conditions may be employed.

When the valve 49 is closed, due to heat absorption in the evaporatorcoil 3|, refrigerant in the coil 3| is evaporated which can no longer bereturned to the compressor and therefore the pressure in the chamber 42of the accumulator increases above the pressure in the chamber 4|. Thiscauses liquid refrigerant to flow through the opening beneath the baiiie40 from the chamber 42 into the chamber 4|. Since the pipe 41 projectsupwardly into the chamber 42 of the accumulator slightly above thebottom of the same as shown, passage of liquid refrigerant from thechambe 42 into the chamber 4| will uncover the upper end of the pipe 41and prevent further passage of liquid refrigerant into pipe 41 therebycutting off the supply of liquid refrigerant to the coil 3|. As nofurther cooling will be accomplished in this coil the capacity of thesystem will be reduced. If the fluid being cooled by the coils 29, 39and 3| rises in temperature due to insufiicient cooling, the valve 49will reopen to permit equalization of refrigerating levels in chambers4| and 42 of the accumulator and liquid refrigerant will again besupplied through the pipe 4'5 to refrigerating coil 3|.

When the valve 49 is closed, forcing liquid from chamber 42 of theaccumulator into chamber 4| the liquid level in chamber-4| may risesufliciently to close the valve 36 which will further reduce thecapacity of the system. However this condition is only temporary for assoonlas the liquid level drops in chamber 4|, valve 36 will reopen,restoring the feeding of liquid refrigerant. If the temperature-of theliquid being cooled drops to a predetermined point, valve 43 will closecutting off the supply of refrigerant from the condenser to all of thecoils until such time as the temperature of the fluid being cooled,rises to open the valve 43. Upon a still further rise in temperature thevalve 49 will be reopened causing coil 3| also to be put into operation.

Expansion valve 39 similarly to expansion valve i9 in Fig. 1 above, isset to supply refrigerant sufficient or somewhat in excess of thatrequired to be evaporated in all the coils of the cooler and therefore amixture of gaseous and liquid refrigerants is withdrawn from each of thecoils Gaseous refrigerant and entrained liquid withdrawn from the coils29 and 30 is separated in chamber M of the accumulator, the gaseousrefrigerant passing to the suction line and the liquid refrigerantdraining down to the line 46. The gaseous refrigerant with entrainedliquid withdrawn from the coil 3| is discharged into chamber 42 of theaccumulator, the gaseous refrigerant passing through pipe 48 intosuction line 35 and the liq-' uid refrigerant draining through pipe 41.If an excess of liquid refrigerant is fed through the valve 39 the levelof liquid refrigerant will rise in the accumulator 34 until the valve 36closes, shutting off the supply. Thereafter liquid refrigerant passingfrom the accumulator through pipes 46 and 41 will pagtially evaporatedue to heat absorption and the level in the accumulator since no liquidis flowing in will be reduced, until the liquid level in the accumulatorhas decreased sufiiciently to cause the opening up of valve 36.

The valves 43 and 49 may be controlled from different points suchaspoints 45 and 5| so that a combination of their location andtemperaturesetting will cause the desired results or if desired the morelogical method is to control both these two valves from the outlettemperatures of the liquid being cooled. Thermostats which control thesevalves are preferably set at slightly difierent temperature levels.

It will be obvious to those skilled in the art that various otherchanges may be made in the construction and arrangement of parts withoutdeparting from the spirit of the invention and therefore the inventionis not limited to what is shown on the drawing and described in thespecification but only as indicated in the appended claims.

I claim:

1. A method of refrigeration comprising supplying liquid refrigerant,evaporating a portion of said liquid refrigerant, withdrawing thevaporous and entrained liquid from the place of evaporation, separatingliquid from the vapor, evaporating a portion of the separated liquid,withdrawing the vaporous and entrained liquid from the second place ofevaporation, separating liquid from the vapor, equalizing the liquidlevel between the two separated liquids, and utilizing part of theentrained liquid from the second separation for a subsequentevaporation.

2. A method of refrigeration comprising supplying liquid refrigerant,evaporating a portion of said liquid refrigerant, withdrawing thevaporous and entrained liquid from the place of evaporation, separatingliquid from the vapor, evaporating a portion of the separated liquid,withdrawing the vaporous and entrained liquid from the second place ofevaporation, separating liquid from the vapor, equalizing the liquidlevel between the separated liquids, utilizing part of theentrainedliquid from the second separation for a subsequent evaporationand utilizing liquid refrigerant from the second separation to out offthe supply for the final evaporation.

3. In a refrigerating system comprising an evaporator formed of aplurality of sections and an accumulator having a plurality of sectionsfor separating entrained liquid refrigerant from gaseous refrigerant,means for supplying liquid refrigerant to one section of the evaporator,means for returning some of the separated liquid to another section ofthe evaporator, equalizing the liquid level between two sections of theaccumulator, and means for cutting off one section of the evaporator.

4. A refrigerating system comprising an evapotor having a plurality ofsections and an accumulator having at least two sections, means forsupplying liquid refrigerant to one of said evaporator sections inexcess of the amount that may be evaporated therein, separating theexcess liquid from the gaseous refrigerant drawn from the evaporator inone section of the accumulator, returning a portion of theseparatedliquid to another section of the evaporator, equalizing theliquid level between the sections of the accumulator, and feeding partof the liquid from the'second section of the accumulator to a thirdevaporator section.

5. A refrigerating system comprising an evaporator having a plurality ofsections and an accumulator having at least two sections, means forsupplying liquid refrigerant to one of said evaporator sections inexcess of the amount that may be evaporated therein, separating theexcess liquid from the gaseous refrigerant drawn from the evaporator inone section of the accumulator, returning a portion of the separatedliquid to another section of the evaporator, equalizing the liquid levelbetween the sections of the accumulator, feeding part of the liquid fromthe second section of the accumulator to a third evaporator section, andmeans for forcing liquid refrigerant from the second section of theaccumulator in a manner to cut off the liquid supply to the thirdsection of the evaporator.

6. A refrigerating system .of connected elements including an evaporatorcomposed of sections,an accumulator,means for supplying refrig-' 'erantdeposited in the accumulator from one evaporator section into anotherevaporator section, means responsive to accumulator liquid level foraltering the refrigerant supplied to the evaporator, and means betweensaid last mentioned means and an evaporator section for restricting therefrigerant supply thereto.

'7. A refrigerating system of connected elements including an evaporatorformed of sections, an accumulator for trapping out liquid entrainedwith gaseous refrigerant as it is drawn from the evaporator, means forsupplying refrigerant deposited in the accumulator into an evaporatorsection, means responsive to accumulator liquid level for altering therefrigerant supply to the evaporator, and means between said lastmentioned means and an evaporator section for restricting therefrigerant supply.

8. The method of refrigeration comprising the stages of supplyingrefrigerant to a first place of evaporation, evaporating a portion ofsaid refrigerant, passing evaporated refrigerant and entrained liquidrefrigerant to a place of separation, separating the liquid refrigerantfrom the' gaseous refrigerant, passing said separated liquid refrigerantto a second place of evaporation, con,- trolling the supply ofrefrigerant to the first place of evaporation in accordance with thequantity of refrigerant fluid passed from the first place ofevaporation, and further restricting said supply to the first place ofevaporation to thereby maintain a. supply of refrigerant in both placesof evaporation.

9. A refrigerating system of connected elements including an evaporatorcomposed of sections, an accumulator, means for supplying refrigerantdeposited in the accumulator from one evaporator section into anotherevaporator section, means for altering the refrigerant supplied to theevaporator, responsive to an excess of refrigerant supplied thereto, andmeans between said last mentioned means and an evaporator section forrestricting the refrigerant supply thereto.

10. A refrigerating system of connected elements including an evaporatorformed of sections, means for supplying'refrigerant to a firstevaporator section, means for supplying refrigerant from said firstevaporator section to a second evaporator section, a valve for shuttingoff the supply of refrigerant to the first evaporator section responsiveto an excess of refrigerant supplied thereto, and a second valve betweenthe first valve and the first evaporator section for restricting thesupply of refrigerant.

W'IILIAM R.

